Continuing on our theme of decimals, today let’s look at adding and subtracting them.
If you know how to add and subtract whole numbers, then adding and subtracting decimals will be simple. The most important thing to remember when adding and subtracting decimals is that you must line up the decimal points when you write the problem vertically. It’s like normal addition and subraction; you’re aiming to line up the place values.
Correct: 16.85 Incorrect: 16.85
- 4.91 – 4.91
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The normal rules about carrying and borrowing apply when you’re adding and subtracting decimals. The above problem, when worked correctly, will involve the 8 borrowing from the 6, and will give us back an answer of 11.94. The decimal point stays lined up with the other numbers in the problem.
Tomorrow, we’ll look at multiplying decimals, which plays by different rules.
