I will teach you a trick how to multiply 2 digit numbers (Note: under 20) quickly without using a calculator this method will take 6 seconds to do. Anyway this method is very useful for me when I was in High School and College I learn this from my Uncle he is a math geek (joke).
Example 1.
14 * 12 =???
I am sure this question takes time in general? here is the solution how you solve this in no time really. first we lets define the problem.
Multiplicand = 14
Multiplier = 12
Product = ???
Step 1: Multiply the last digit of the multiplicand and the last digit of multiplier.
In this example: 4 * 2 = 8
Step 2: Add the multiplicand and the last digit of the multiplier.
In this example:14 + 2 = 16
Step 3: Now combine the sum of step 2 which is (16) and the product of step 1 which is (8) So the final Answer is 168. Easy Right?
Example 2.
Ok let’s try 13X12 = ???
Step 1: 3 * 2 = 6
Step 2: 13 + 2 = 15
Step 3: 156
Lets move to a bit complicated ones:
17 * 18 = ???
Step 1: 7 * 8 = 56
Step 2: 17 + 8 =25
Step 3: 306
How ??
Step 3: in this this case the product of the step 1 is 2 digit number which is (56) so the trick here is we take the last digit of 56 and it will the last digit of our final answer.
Like in this case:
56 is the result of step 1
So 6 will be the last digit of the final answer.
We will add the first digit of step 1 (in this case it is 5) to the answer of step 2.
So 25 + 5 = 30
So answer will be 306
wait what??? I'm Confused?
Here is an explanation in 4 steps for this scenarios
Lets take new numbers 16 * 14 = ???
Step 1: 6 * 4 = 24
Step 2: 16 + 4 = 20
Step 3: 20 + 2 = 22
Step 4: 224
What we did in here is we just amended the last digit of step 1 to step 3 and that becomes your final answer
Last Example
15 * 14 = ???
Step 1: 5 * 4 = 20
Step 2: 15 + 4 = 19
Step 3: 20 + 1 = 21
Step 4: 210
If you guys have any doubt's or questions just comment below and i will reply as soon as i can.
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