Multiplying 2 digit number by 1 digit number

In this section you will learn multiplying 2 digit number by 1 digit number.
In the earlier section , you have learnt about the multiplication of numbers on the number line as well as without number line.
There are different methods to do the multiplication of two digit number by one digit.
Method 1 :
Example : A flower has five petals. A bunch of flowers has 13 flowers. How many petals are there in the bunch?
Solution : Total flowers = 13
Number of petals in each flower = 5
So total number of petals = 13 X 5
Write 13 as 10 + 3
10 X 5 = 50
3 x 5 = 15
Total petals = 50 + 15 = 65.
Method 2 :
23 x 3 :
This method is known as vertical method.
1) Write the bigger number.
2) Give the multiplication sign (x).
3) Write the 2nd number.
4) Multiply the 2nd number by the digit in ones place and write the answer.
5) Multiply the tens number by the 2nd number and write the answer using tens.
  23 ---->
X 3 ----->
________

∴ 23 x 3 = 69

 2 tens + 3 ones
X 3
______________
6 tesn + 9 ones
60 + 9
= 69

3) 36 x 0
  36 ---->
X 0 ----->
________

∴ 36 x 0 = 0
When you multiply any number by zero the answer will be 0(zero) only.
3 tens + 6 ones
X 0
______________
0 tens + 0 ones
0 + 0
= 0



Examples on multiplying 2 digit number by 1 digit number

1) A design has 3 flowers in it. A piece of cloth has 12 such designs. How many flowers will be on the cloth? Solution : Number of flowers in one design = 3
Total number of designs = 12
∴ Total number of flowers = 12 x 3
  12
X 3
_________
3 ← 6
3 tens + 6 ones
= 36
Hence, 12 x 3 = 36.
1) Write the bigger number '12'.
2) Give the multiplication sign (x).
3) Write the 2nd number '3'.
4) Multiply the 2nd number(3) by the digit in ones place(2) and write the answer as 6 ones .
5) Multiply the tens number(1) by the 2nd number(3) and write the answer as 3 tens.
6) 3 tens + 6 ones = 30 + 6 = 36.
∴ Total number of flowers= 36.

2nd grade math

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