Subtracting within 100

How to subtract within 100

Write the numbers in a column: ones under ones, tens under tens. Subtract the ones first, then the tens.

Example 1: 68 − 25 (no regrouping)

$\begin{array}{r}68\\-\,25\\\hline 43\end{array}$

1. Ones: ${8 - 5 = 3}$.
2. Tens: ${6 - 2 = 4}$.

So ${68 - 25 = 43}$.

Example 2: 52 − 27 (with regrouping)

$\begin{array}{r}52\\-\,27\\\hline 25\end{array}$

1. You can't take 7 ones from 2 ones, so take 1 ten from the 5 tens. Now you have 4 tens and 12 ones.
2. Ones: ${12 - 7 = 5}$.
3. Tens: ${4 - 2 = 2}$.

So ${52 - 27 = 25}$.

Check by adding: ${25 + 27 = 52}$. If you get the top number back, your answer is right.

Want only problems with regrouping? Try the Subtraction with Regrouping worksheet.