Division with decimal numbers

If you watched the video about multiplication of decimals, you should know several simplifying tricks. Now we're going to look at division by decimals. There are several good tricks here as well. Imagine the world's longest candy string. 20 metres long.

If you cut it into pieces 10 metres long, 20 divided by 10 equals 2 2 pieces, you divided the string in half. If you cut the whole string into half metre pieces, 0,5 metres long, how many pieces will you get? Here's a trick: Dividing a number by 0.5 gives the same result as multiplying the number by 2 There are two 0.5 metre pieces in every metre. So, instead of dividing 20 by 0.5, we can just multiply 20 by 2. The result will be the same, no matter which way you calculate it.

20 divided by 0.5 equals 40 2 times 20 equals 40 40 pieces of string. If you cut the string into pieces that are 0.1 metres long, how many pieces will there be? Here's the trick: Dividing a number by 0.1 gives the same result as multiplying the number by 10. There are ten 0.1 metre pieces in every metre. 10 times 20 equals 200 So, instead of dividing 20 by 0.1, you can multiply 20 by 10.

The result is the same, whichever calculation method you use. 20 divided by 0,1 equals 200 200 pieces When you divide a number less than 1, the answer will always be larger than the initial number. The world's longest candy string would be enough for 200 people if everyone got 0.1 metres, or 1 decimetre, or 10 cm of string. There is a fruit sale at the market again. You bought 0,8 kilograms of oranges for 12 kronor.

How much does one kilogram of oranges cost? In order to calculate this, it is useful to know several tricks: When you divide by a number that ends in zeros, you can simplify it by dividing by 10, 100 or 1000. Example: 1.5 divided by 30 To have a single digit denominator we need to divide by 10 1,5 divided by 10 equals 0,15 and 30 divided by 10 equals 3 which gives 0.15 divided by 3 which is equal to 0.05 Another example: 150 divided by 300 Here to have a single digit denominator we have to divide by 100 150 divided by 100 equals 1.5 and 300 divided by 100 equals 3 which gives 1.5 divided by 3 which is equal to 0.5 When you divide a decimal number, you can expand it by 10, 100 or 1000. 15 divided by 0.3 We expand the decimal by 10 so that we have an integer in the denominator. 15 times 10 equals 150 and 0.3 times 10 equals 3 150 divided by 3 is equal to 50 0,15 divided by 0,03 equals?

Here we expand the decimal by 100, so that we have an integer in the denominator. 0.15 times 100 equals 15 and 0.03 times 100 equals 3 which gives 15 divided by 3 equals 5 How much then is a kilogram of oranges? You paid 12 kronor for 0.8 kilograms of oranges. To calculate the price of one kilogram, in kronor per kilogram, you divide 12 kronor by 0.8 kilogram Now you can use the tricks you learned. Expand by 10 so that you get an integer in the denominator.

12 times 10 equals 120 and 0.8 times 10 equals 8 which gives 120 divided by 8 equals 15 The answer is reasonable because 12 divided by 1 equals 12 12 divided by 0.8 should therefore be somewhat larger than 12 The answer is always larger than the initial number when you divide by a number less than 1 Your oranges cost 15 kronor per kilogram.