Division as a mental calculation

The result of division can usually be deduced through multiplication. Below are some tips for working with the figures:

If both numbers end in 0, then the numbers can be divided by 10.
If both numbers are even, then the numbers can be divided by 2.
If both numbers end in 5, then you can divide the numbers by 5.
If one of the numbers ends in 0 and the other in 5, you can divide them by 5.
If the sum of the digits of the number is divisible by three, then you can divide the number by 3.

Use these to continue to reduce the numbers, so you can deduce the result without a calculator. If you can't find anything in common, then there is nothing you can do about the bill. Example 1: Calculate

In this example, the sum of the digits in the number 72 is 7+2 = 9, i.e. it is divisible by 3. Example 2: Calculate

For large numbers, you should start with easy numbers, such as 2, 5 and 10, and proceed slowly. Example 3: Calculate

Example 4: Calculate

Example 5: Calculate

The examples do not try to take the calculations to the end result as quickly as possible, but show a conceptual Reducing the numbers gradually.

Division as a mental calculation

Division as a mental calculation

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