Dividing by 0.5. A simple method to divide by a half by doubling the number.

A quick way to divide by 0.5 or ½ is to double the number (or multiply number by 2). The reason for this is because two halves go into a whole. If you still can’t see why you double the number, just think about an easy example, such as, 3 ÷ 0.5. Go through your multiples of 0.5 until you reach 3:

0.5, 1, 1.5, 2, 2.5, 3...

As you can see 3 is the 6th multiple of 0.5, so the answer to 3 ÷ 0.5 is 6.

Another thing to remember is that when you divide by a decimal between 0 and 1 the answer is larger than the number that you started off with.

Let’s look at some harder questions that involve dividing by 0.5:

Example 1

Work out the answer to 26 ÷ 0.5.

All you need to do is double the number, as dividing by 0.5 is the same as multiplying by 2:

26 ÷ 0.5 = 26 × 2 = 52.

Example 2

Work out the answer to 57 ÷ 1/2:

Again all you need to do is double the original number, as dividing by ½ is the same as multiplying by 2:

57 ÷ ½ = 57 × 2 = 114.

Example 3

Find the value of 428 ÷ 0.5:

Again, double the number you are dividing:

428 + 428 = 856.

Example 4

Work out an estimate to 726.854 ÷ 0.478.

When carrying out an estimate round all the numbers off to 1 significant figure:

726.854 = 700

0.478 = 0.5

All you need to do now is work out 700 ÷ 0.5. Just like the last 3 examples this can be done by multiplying 700 by 2:

700 ÷ 0.5 = 700 × 2 = 1400.

So an estimate to the calculation 726.854 ÷ 0.478 is 1400.

Example 5

How many pieces of wood 0.5m long can be cut from a plank of wood of length 9m.

Here you need to work out how many 0.5’s go into 9:

9 ÷ 0.5 = 9 × 2 = 18

So 18 pieces of wood can be cut from the plank of wood.

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