# Adding and Subtracting Decimals

We usually add numbers when we have different and varied data, but when we are given with a set of repeated data, we **multiply.**

### Multiplication is a much easier way to calculate repeated data.

**2 ****Ã— 3 **also means **2 + 2 + 2** which is equal to **6.**

** Example:** Letâ€™s say Jim buys 4 pens costing $3.50 each. What is the total cost?

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 3.50**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 3.50**

Cost of one pen = **$3.50Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 3.50Â Â **

Hence, the cost of 4 pens **= $****3.50 Ã— 4Â Â Â Â Â Â Â Â + 3.50**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â _________**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 14.00**

### Why is place value important when adding and subtracting decimals?

**Letâ€™s look at this example now:Â Â Â 2.87 + 3.02 + 0.006 + 123.9 + 4**

** Example:** RenÃ©e bought 6.75 pounds apples, 4.5 pounds oranges, 3.82 pounds bananas and 2.25 pounds grapes. How much of fruits did she buy in all?

** Solution:** Fruits RenÃ©e bought in all = 6.75 + 4.5 + 3.82 + 2.25 =

**17.32 pounds**

### How do you subtract with decimals?

Subtracting decimals is much similar to the way we have learnt above in adding decimals. Letâ€™s see how.

** Example:** Daniel has 2 pieces of wood measuring, 10.34 inches and 7.56 inches. How much longer is the first piece than the second one?

Subtract the lengths of 2 given wooden pieces.Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â **10.34**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â –7.56**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â _________**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 2.78**

So, the first piece is 2.78 inches longer than the second wooden piece.

**Check pointÂ Â Â Â **

Add the following decimals:

- 3.25 + 1.32 + 4.67
- 1.46 + 2.35 + 1.00

Subtract the following decimals:

- 5.82 â€“ 1.23
- Richard has 100.56 pounds of grain out of which he 34.156 pounds to his brother, John. How many pounds of grain is Richard left with?
- A box of peanut butter cookies cost $3.40 and a box of oatmeal cookies cost $4.25. What is the total cost for both cookies boxes?

- Mary has 20.752 inches of ribbon out of which she used 12.456 inches of ribbon for decorating purpose. How much ribbon is she left with?

**Answer KeyÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â **

- 9.24
- 4.81
- 4.59
- 66.404 pounds
- $7.65
- 8.296 inches

*Download/Solve aÂ WorksheetÂ for Adding and Subtracting Decimals*