Subtraction Within 100

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Answer Key & Explanations

Subtraction Within 100 · Grade 2 · Worksheet 3

1. 92 - 57 = ? Answer: 35 Solution: 92 -57 Look at the ones place: 2 - 7. Since 2 is smaller than 7, we need to regroup. Take 1 ten from the 9 tens, leaving 8 tens.
   Full step-by-step solution

   Step 1: Write the problem vertically: 92 -57 --- Step 2: Look at the ones place: 2 - 7. Since 2 is smaller than 7, we need to regroup. Step 3: Take 1 ten from the 9 tens, leaving 8 tens. Add 10 ones to the 2 ones, making 12 ones. Step 4: Now subtract in the ones place: 12 - 7 = 5 Step 5: Subtract in the tens place: 8 - 5 = 3 Step 6: Combine the results: 35 The answer is 35.

2. 72 - 38 = ? Answer: 34 Solution: 72 - 38 Start subtracting from the rightmost column (ones place). In 72, the ones digit is 2. In 38, the ones digit is 8.
   Full step-by-step solution

   Let's solve 72 - 38 step by step. Step 1: Write the problem vertically in your mind: 72 - 38 Step 2: Start subtracting from the rightmost column (ones place). In 72, the ones digit is 2. In 38, the ones digit is 8. Since 2 is smaller than 8, we cannot subtract directly. Step 3: We need to borrow from the tens place. The 7 in the tens place of 72 means 7 tens, which is 70. Take 1 ten from the 7 tens, leaving 6 tens. That 1 ten equals 10 ones. Add these 10 ones to the existing 2 ones: 10 + 2 = 12 ones. Step 4: Now subtract the ones column: 12 ones - 8 ones = 4 ones. Write down 4 in the ones place of the answer. Step 5: Move to the tens column. After borrowing, the tens digit of 72 is now 6 (not 7). Subtract the tens: 6 tens - 3 tens = 3 tens. Write down 3 in the tens place of the answer. Step 6: Combine the digits: 3 tens and 4 ones gives 34. Therefore, 72 - 38 = 34.

3. 83 - 46 = ? Answer: 37 Solution: 83 -46 Look at the ones place: 3 - 6. Since 3 is smaller than 6, we need to regroup. Take 1 ten from the 8 tens, leaving 7 tens.
   Full step-by-step solution

   Step 1: Write the problem vertically: 83 -46 --- Step 2: Look at the ones place: 3 - 6. Since 3 is smaller than 6, we need to regroup. Step 3: Take 1 ten from the 8 tens, leaving 7 tens. Add 10 ones to the 3 ones, making 13 ones. Step 4: Now subtract in the ones place: 13 - 6 = 7 Step 5: Subtract in the tens place: 7 - 4 = 3 Step 6: Combine the results: 3 tens and 7 ones = 37 The answer is 37.

4. Liam has 75 marbles in his collection. He gives 28 marbles to his friend Noah. How many marbles does Liam have left? Answer: 47 Solution: Liam starts with 75 marbles He gives away 28 marbles Subtract 28 from 75: 75 - 28 First subtract the ones: 5 - 8, can't do, so borrow from tens 75 becomes 6 tens and 15 ones 15 ones - 8 ones = 7 ones 6 tens - 2 tens = 4 tens Combine tens and ones: 40 + 7 = 47 The answer is 47.
   Full step-by-step solution

   Step 1: Liam starts with 75 marbles Step 2: He gives away 28 marbles Step 3: Subtract 28 from 75: 75 - 28 Step 4: First subtract the ones: 5 - 8, can't do, so borrow from tens Step 5: 75 becomes 6 tens and 15 ones Step 6: 15 ones - 8 ones = 7 ones Step 7: 6 tens - 2 tens = 4 tens Step 8: Combine tens and ones: 40 + 7 = 47 The answer is 47.

5. Liam had 85 marbles in his collection. He gave 27 marbles to his friend Noah at school. How many marbles does Liam have left? Answer: 58 Solution: Start with Liam's original marbles: 85 Subtract the marbles he gave away: 85 - 27 Break it down: 85 - 20 = 65, then 65 - 7 = 58 The answer is 58 marbles.
   Full step-by-step solution

   Step 1: Start with Liam's original marbles: 85 Step 2: Subtract the marbles he gave away: 85 - 27 Step 3: Break it down: 85 - 20 = 65, then 65 - 7 = 58 Step 4: The answer is 58 marbles.

6. Emma had 92 stickers in her sticker book. She used 45 stickers to decorate her art project. How many stickers does Emma have left in her sticker book? Answer: 47 Solution: Start with 92 stickers Subtract 45 stickers that were used Since we can't subtract 5 from 2 in the ones place, we need to regroup Take 1 ten from the 9 tens, leaving 8 tens Add that 1 ten (which is 10 ones) to the 2 ones, making 12 ones Now subtract: 12 ones minus 5 ones equals 7 ones 8 tens…
   Full step-by-step solution

   Step 1: Start with 92 stickers Step 2: Subtract 45 stickers that were used Step 3: Since we can't subtract 5 from 2 in the ones place, we need to regroup Step 4: Take 1 ten from the 9 tens, leaving 8 tens Step 5: Add that 1 ten (which is 10 ones) to the 2 ones, making 12 ones Step 6: Now subtract: 12 ones minus 5 ones equals 7 ones Step 7: 8 tens minus 4 tens equals 4 tens Step 8: Combine the results: 4 tens and 7 ones equals 47 Emma has 47 stickers left.

7. Mrs. Johnson's class has 64 crayons. They use 28 crayons for an art project. How many crayons are left? Answer: 36 Solution: Start with 64 crayons total Subtract 28 crayons that were used 64 - 28 = ?
   Full step-by-step solution

   Step 1: Start with 64 crayons total Step 2: Subtract 28 crayons that were used Step 3: 64 - 28 = ? Step 4: Subtract the ones place: 4 - 8, we need to borrow from the tens place Step 5: 64 becomes 5 tens and 14 ones Step 6: 14 - 8 = 6 Step 7: 5 - 2 = 3 Step 8: So 64 - 28 = 36 The answer is 36.

8. 85 - 37 = ? Answer: 48 Solution: Start with 85 - 37 Subtract the ones place: 5 - 7 (can't do this, so regroup) Take 1 ten from 8 tens, making it 7 tens, and add 10 ones to 5 ones, making 15 ones Now subtract ones: 15 - 7 = 8 Subtract tens: 7 - 3 = 4 Combine the results: 4 tens and 8 ones = 48 The answer is 48.
   Full step-by-step solution

   Step 1: Start with 85 - 37 Step 2: Subtract the ones place: 5 - 7 (can't do this, so regroup) Step 3: Take 1 ten from 8 tens, making it 7 tens, and add 10 ones to 5 ones, making 15 ones Step 4: Now subtract ones: 15 - 7 = 8 Step 5: Subtract tens: 7 - 3 = 4 Step 6: Combine the results: 4 tens and 8 ones = 48 The answer is 48.

9. 76 - 38 = ? Answer: 38 Solution: 76 -38 Look at the ones place: 6 - 8. Since 6 is smaller than 8, we need to regroup. Take 1 ten from the 7 tens, leaving 6 tens.
   Full step-by-step solution

   Step 1: Write the problem vertically: 76 -38 --- Step 2: Look at the ones place: 6 - 8. Since 6 is smaller than 8, we need to regroup. Step 3: Take 1 ten from the 7 tens, leaving 6 tens. Add 10 ones to the 6 ones, making 16 ones. Step 4: Now subtract in the ones place: 16 - 8 = 8 Step 5: Subtract in the tens place: 6 - 3 = 3 Step 6: Combine the results: 3 tens and 8 ones = 38 The answer is 38.

10. 45 - 18 = ? Answer: 27 Solution: Write the problem vertically in your mind, aligning the digits by place value (ones and tens). 45 - 18 Start by subtracting the numbers in the ones column (rightmost column). We have 5 - 8.
    Full step-by-step solution

    Let's solve 45 - 18 step-by-step. Step 1: Write the problem vertically in your mind, aligning the digits by place value (ones and tens). 45 - 18 Step 2: Start by subtracting the numbers in the ones column (rightmost column). We have 5 - 8. Since 5 is smaller than 8, we cannot subtract directly. We need to borrow from the tens column. Step 3: Borrow 1 ten from the 4 in the tens column. 1 ten is the same as 10 ones. So, the 4 in the tens place becomes 3 (because we borrowed 1), and the 5 in the ones place becomes 15 (5 + 10). So now we have: Tens column: 3 (after borrowing) Ones column: 15 Step 4: Now subtract the ones column: 15 - 8 = 7. Write down 7 in the ones place of the answer. Step 5: Now subtract the tens column: 3 - 1 = 2. Write down 2 in the tens place of the answer. Step 6: Combine the digits from the tens and ones columns: 2 and 7 gives 27. So, 45 - 18 = 27.