how to multiply numbers quickly ?
Answers
Memorise multiplication tables upto 10
To multiply numbers between 10 and 20 you can either memorise the tables or use this simple trick that helps you multiply in your head
The trick basically involves adding the units digit of one number with the other and multiplying the units digit of both the numbers.
Example 1: 12 x 13
Step 1: Divide the solution into two parts : 12x13 => ? | ?
Step 2: Left part is obtained by adding either of the numbers with the units digit of the other number : 12 + 3 or 13 + 2 => 15. Thus we have 12x13 => 15 | ?
Step 3 : Next, right part is obtained by taking the product of units digits : 2x3 = 6.
Thus 12 x 13 = 156
Example 2: 16 x 14
Calculating the left and right parts as in previous example, we get 16 x 14 = 20 | 24. But note that the right part cannot contain more that 1 digit. The excess digit if any will be carried to the left part. In this case 2 in 24 will carried to left. Thus 16x14 = 224
To multiply any two digit number you can use the vertical and crosswise technique from Vedic maths to multiply numbers from left to right in your head
Example: 24 x 36
Step 1: Divide the solution into three parts => ? | ? | ?
Step 2: Left most part is obtained by multiplying the tens digit of both the numbers : 2x3=6. Hence we have 24x36 => 6 | ? | ?
Step 3: Middle part is obtained by cross multiplying 2 and 6, 3 and 4 and then adding the respective products : 2x6 + 3x4 = 24. Thus 24x36 => 6 | 24 | ? . Note: Except for the left most part all the other parts cannot contain more than 1 digit. Hence the excess digit 2 in middle part will be carried over to its immediate left part. Thus 24x36 => 8 | 4 | ?
Step 4: Right most part is obtained by taking the product of units digits : 4x6 => 24. Now, since the number of digits is greater than 1, the excess digit 2 in 24 will be carried to its immediate left part. Thus 24x36 => 864
You can extend the above vertical and cross wise technique to multiply any two three digit numbers as well. The three digit multiplication involves 5 steps. I have summarised these steps in a visual way that you may find easier to learn and understand in an app, the link to which i shared below
Once you learn these tricks you will have to practice them regularly. This is where i believe you may find this app - Math Tricks Workout helpful. Math Tricks Workout is purely a workout based free app organised into level based tasks. The workouts are coupled with some of the mental Math Tricks that you may find useful while taking the workouts
Answer:
"To multiply two 2-digit numbers without showing work, first multiply the ones digits together, then 'cross-multiply,' and finally multiply the tens digits together.
Make sure to carry whenever a product exceeds 9. As you will see in the examples below, you must work your way from right to left to perform this trick.
EX 1:
12 x 23 = ?
Multiply the ones digits: 2x3=6 (ones digit answer).
Cross-multiply and add: (1x3)+(2x2)=7 (tens-digit answer).
Multiply the tens digits: 1x2=2 (hundreds-digit answer).
Combine: 276 (the answer).
Step-by-step explanation: