• Write down the numbers, one under the other, with the decimal points lined up
• Put in zeros so the numbers have the same length (see below for why that is OK)

### Example: Add 1.452 to 1.3

 Line the decimals up: 1.452 + 1.3 "Pad" with zeros: 1.452 + 1.300 Add: 1.452 + 1.300 2.752

### Example: Add 3.25, 0.075 and 5

 Line the decimals up: 3.25 0.075 + 5. "Pad" with zeros: 3.250 0.075 + 5.000 Add: 3.250 0.075 + 5.000 8.325

That's all there is to it - just remember to line up the decimals, pad with zeros, then add normally.

## Subtracting

To subtract, follow the same method: line up the decimals, then subtract.

### Example: What is 7.368 − 1.15 ?

 Line the decimals up: 7.368 − 1.15 "Pad" with zeros: 7.368 − 1.150 Subtract: 7.368 − 1.150 6.218

### Example: Check that 7.368 minus 1.15 equals 6.218

Let us try adding 6.218 to 1.15

 Line the decimals up: 6.218 + 1.15 "Pad" with zeros: 6.218 + 1.150 Add: 6.218 + 1.150 7.368

It matches the number we started with, so it checks out.

### Putting In Zeros

Why can we put in extra zeros?

A zero is really saying "there is no value at this decimal place".

• In a number like 10, the zero is saying "no ones"
• In a number like 2.50 the zero is saying "no hundredths"

So it is safe to take a number like 2.5 and make it 2.50 or 2.500 etc

But DON'T take 2.5 and make it 20.5, that is plain wrong.