2nd Grade Subtracting Within 100 Quiz: 10 Questions with Explanations

A \(67\)B \(37\)C \(27\)D \(17\)

Take away 2 tens from 4 tens to get 2 tens. The 7 ones stay, so the answer is 27.

A \(27\)B \(37\)C \(33\)D \(23\)

After crossing out 1 ten and 8 ones, 2 tens and 7 ones are left, or 27. Taking the smaller digit from the larger gives the wrong 33.

A \(45\)B \(25\)C \(37\)D \(35\)

Two jumps back mean 71 – 30 = 41 and 41 – 6 = 35. Forgetting the second jump gives 41, and forgetting to cross a ten gives 45.

A \(35\)B \(101\)C \(15\)D \(25\)

The missing part is 63 – 38 = 25. Subtracting 3 – 8 as 8 – 3 gives the wrong 35, and adding gives 101.

A The number 72 is an even number.B The tens must be larger than the ones.C There are only 2 ones and 5 ones must be taken away.D The number 7 is greater than the number 4.

Two ones are not enough to take away 5 ones, so a ten is traded for ten ones. The value of 72 does not change.

A \(57\)B \(43\)C \(53\)D \(47\)

Trade 1 ten: 8 tens and 10 ones. Then 10 – 7 = 3 and 8 – 4 = 4, so the answer is 43.

A \(27 + 61 = 88\)B \(27 + 34 = 61\)C \(61 + 34 = 95\)D \(34 – 27 = 7\)

Add the difference to the number taken away to get the whole: 27 + 34 = 61.

A \(26\)B \(34\)C \(36\)D \(24\)

Jamal subtracted the smaller digit from the larger in each place. Trade 1 ten instead: 4 tens and 13 ones, so 13 – 7 = 6 and 4 – 2 = 2, which makes 26.

A \(53\)B \(47\)C \(57\)D \(123\)

Subtract 85 – 38. Trade 1 ten: 7 tens and 15 ones, so 15 – 8 = 7 and 7 – 3 = 4, which makes 47. Adding gives the wrong 123.

A \(+3, +20\)B \(+3, +30\)C \(+20, +30\)D \(+7, +20\)

From 57, +3 reaches 60 and +20 reaches 80. The jumps add to 23, which is the difference.