How do I improve my arithmetic skills?

1. Round Off to a Quick Approximation

First determine a level of accuracy you are happy with, then round the numbers appropriately before making the calculation. This is also useful to determine a quick ballpark figure before doing the actual calculation.

2. Break Up Into Parts

Say you have to multiply 613 by three. Try multiplying first 600 by 3, then 10 by 3 then 3 by 3 and adding the results.

3. Omit Words

When calculating in your head, think of the results rather than saying out the words. For example to compute 30/2, just think 15 instead of thirty divided by two equals fifiteen.

4. Quickly Find Three Common Percentages

20% -> Divide the number by 5
33.3% -> Divide the number by 3
50% -> Divide the number by 2

5. Finding Percentages by Using 100’s

The percentage of a hundred is the percentage number itself. For example, 15% of 100 is 15. Use this, combined with the Break Up Into Parts method.

Another tip that I use sometimes…

When multiplying (or dividing) 2 numbers together that may seem difficult…

32 x 62 = ?

This equation is the same as 16 x 124, which is the same as 8 x 248, which is the same as 4 x 496, or 2 x 992… and anything multiplied by 2 is easy… so
32 x 62 = 1984