In this instructable, I will teach you an easy method I created for multiplying numbers between 1 and 100 with relative ease.
All I ask is that you have a decent understanding of math
Step 1: Pick two numbers
Step 2: Dissect the numbers
19 x (10 + ((1/2) 10))
15 x (20 - 1)
Now the first one might seem a little harder, but it's really not. If you have a five in the equation, you can simply multiply a number by 10 (which is simple, just add a 0 at the end), and then take half of it. So 19 x 5 = half of 19 x 10.
That means that 19 x 5 = (1/2) 190
But for now, let's just stick with the second equation because it is simpler.
Step 3: Multiply out
The distributive property states that we can distribute the 15 to the other numbers, meaning we have (15 x 20) - (15 x 1)
I am sorry for these really short pages, btw.
Step 4: Do some more simple math
Since multiplication has the commutative property, it doesn't matter what order we multiply the numbers in. 15 x 10 x 2 is exactly the same as 10 x 2 x 15, and 2 x 15 x 10, using that rule, we can find that:
2 x (15 x 10) = 2 x 150 = 300
and since we still have to subtract 15 x 1 (which equals 15), we just subtract 15 from 300, giving us 285