Subtracting Tens and One-Digit Numbers

When we subtract from a two-digit number, it helps to look at the tens and ones places. In Grade 1, we learn how to subtract a one-digit number or a group of tens without needing to borrow or regroup.

Subtracting a One-Digit Number

When you subtract a one-digit number from a two-digit number, you only need to subtract the ones. The tens place stays exactly the same!

Let's look at an example: $48 - 3 = ?$

• Look at the ones: $48$ has $8$ ones. We want to take away $3$ ones.
• Subtract the ones: $8 - 3 = 5$.
• Keep the tens: The $4$ in the tens place stays a $4$.

So, $48 - 3 = 45$

Subtracting Tens

When you subtract a multiple of ten (like $10, 20,$ or $30$) from another number, you only change the tens place. The ones place stays the same because you are subtracting zero ones.

Example 1: Subtracting tens from tens

$70 - 30 = ?$

• $70$ is $7$ tens. $30$ is $3$ tens.
• Subtract the tens: $7 - 3 = 4$ tens.
• $4$ tens is $40$.

So, $70 - 30 = 40$

Example 2: Subtracting tens from a two-digit number

$56 - 20 = ?$

• Look at the tens: $56$ has $5$ tens. $20$ has $2$ tens. Subtract them: $5 - 2 = 3$ tens.
• Look at the ones: $56$ has $6$ ones. $20$ has $0$ ones. Subtract them: $6 - 0 = 6$ ones.
• Put the $3$ tens and $6$ ones together.

So, $56 - 20 = 36$

A Quick Rule to Remember

Always subtract ones from ones and tens from tens! If you are only taking away ones, the tens stay the same. If you are only taking away tens, the ones stay the same.