Mental Math Subtraction

Front

What is mental math subtraction?

Back

Mental math subtraction is a method of performing subtraction calculations in your head without using paper or a calculator.

Front

What does it mean to regroup in subtraction?

Back

Regrouping in subtraction means rearranging the numbers to make the subtraction easier, often by borrowing from the next highest place value.

Front

What is the first step in subtracting 90 - 48 using mental math?

Back

Add 2 to 48 to make it easier to subtract.

Front

What do you do after subtracting 90 - 50 in the example of 90 - 48?

Back

You should add 2 to the result of 40.

Front

When subtracting 63 - 39, what should you add first?

Back

You should add 1 to 39.

Front

What is the result of 84 - 49 if you add 1 to 49 first?

Back

The result is 34, and then you should add 1 to 34.

Front

Do you need to regroup to subtract 72 - 47?

Back

Yes, you need to regroup.

Front

In the subtraction problem 43 - 27, which number should you round?

Back

You should round 27.

Front

What is the purpose of rounding in mental math subtraction?

Back

Rounding makes it easier to perform subtraction by simplifying the numbers.

Front

What is the result of 90 - 48 using mental math?

Back

The result is 42.