Maths may not be your thing but it is hard to avoid in
For some games with numbers
To calculate the total of a bill including tax add 1 before multiplying.
This also works in reverse –
In reverse –
Thanks to KB for this one.
What this is actually doing is acknowledging the original figure
Anything ending in an “even” number is divisible by 2.
Anything divisible by 9 is also divisible by 3.
Thanks to KB for these.
A quick way to do calculations is to drop the noughts at the ends
Example – To add 120 + 90 add
If you have to multiply a large number by 25, add two noughts to
Example: 167 x
When faced with a little poser like 27.5% of 50 for example, I
Thanks for these Harvey Alexander
When multiplying numbers ending in 5 by themselves e.g. 75 x 75
Deal with the left hand numbers first
In this example the left-hand number is 7
Add 1 to this number i.e. 7 + 1 = 8
Multiply the original number 7
Now deal with the right-hand numbers which are always 5 x 5 = 25
Therefore the answer is 5625
Here is another example –
35 x 35
3 + 1 = 4
4 x 3 = 12
5 x 5 = 25
Thanks to Allan Brown for this contribution
To make complex sums easier to handle, break down into simpler elements.
Example: 6 x 348
A quick way to convert kilometres to miles is to drop the last digit and multiply by 6.
Example: 72 kilometres = 7 x 6 = 42 miles