What is 27 plus 34?

• A. 61
• B. 60
• C. 66
• D. 65

Answer: (A)

Adding two two-digit numbers involves lining up the ones and tens and using a carry when the ones place sums to 10 or more. For 27 and 34, start with the ones: 7 plus 4 equals 11. Write down the 1 and carry 1 to the tens column. In the tens place, 2 plus 3 equals 5, and including the carried 1 makes 6. So the total is 61. You can also think of it by breaking 34 into 30 and 4: 27 plus 30 is 57, plus 4 is 61. The carry from the ones is what pushes the total past 60 to 61. If the carry were forgotten, you’d get 60; miscounting the tens could give numbers like 65 or 66, but the correct sum is 61.