I had a friend who showcased brilliant mental Mathematical prowess. She could do basic Arithmetic much faster than we type in the digits in our calculator. A gift that came very helpful when trying to figure out the cut all of us needs to put at the bill or while getting our balance back. Today let me share with you some very easy steps to do otherwise complex Arithmetic problems.
1. Multiplying by the Powers of 5
The trick with the powers of 5 is to recognize that the numbers obtained are always a multiple of 10 divided by an integer.
21 x 25
The trick here is to recognize that 25 = 100 / 4.
21 x 25 = 36 x (100 / 4)
Since we can quickly figure out that 21 x 100 = 2100, it’s easy to find that 21 x 25 = 2100 / 4 = 525.
2. Multiplying by 9s
You can multiply the other number by the next higher power of 10 and then subtract one from the product thus obtained.
33 x 99
The trick here is to simply recognize that this is the same as 33 x (100 – 1) = (33 x 100) – 33 =3267.
3. Double and Half to Multiply Fast
The trick here is to continually double one number while halving the other, and then perform the calculation.
47 x 24
In such cases always half an even number and double the odd number
47 x 24 = 94 x 12 = 188 x 6 = 376 x 3 = 1,128
Here at MathsOne, one of the top Maths Tuition Centers in Kerala we teach kids an index of such clever tips to solve the questions at lightning speed