Mathematics Village
Multiplying By 101
Multiplying
By 101
When multiplying a 2 digit number by
101, simply write the number down twice.
53 x 101 = 5353.49 x 101 = 4949.
B. Sometimes there are variations of 101 like 201, 203, 104, etc. In problems like these you can use the following:
23 x 203 =_________.
a) Multiply 23 x 2 = 46.b) Multiply 23 x 3 = 69.
c) The answer is 4669.
When multiplying a 3 digit number by
101 the following rules apply:
1. Write down the last 2 digits of
the number.
2. Take the number in the hundred’s
digit and add back to the number.
453 x 101 =_________.
a) Write 53.b) 4 + 453 = 457. Write 457
c) The answer is 45753.
Ex [2] 998 x 101 =_________.
a) Write 98.b) 9 + 998 = 1007. Write 1007.
c) The answer is 100798.
Shortcut for Multiplication by 11
Multiplication by 11
Multiplication
by 11 is easy! To multiply by a 2-digit number add the two digits and place the
sum in between!
25
x 11 = 275
2 (2+5) 5
2 7 5
31 x 11 = 341
3 ( 3+1) 1
3 4 1
57 x 11 = 627 (you need to carry the 1)
5 ( 5+7) 7
5 ← 1 2 7
6 2 7
What about a 3or 4-digit number? Can you figure out what's going on here?
253 x 11 = 2783
2 (2+5) (5+3) 3
2 7 8 3
2 (2+5) (5+3) 3
2 7 8 3
1857 x 11 = 20427
1 (1+8) (8+5) (5+7) 7
1 9 ←1 3←1 2 7
2 0 4 2 7
PICK A NUMBER GAME
PICK A NUMBER GAME
Pick a number ………………………………..
+ Add 26 to number
+ Add 8 to it
-
Subtract 14 to it
+ Add
6 to it
+ Add
10 to it
Subtract original number form it
WHAT ANSWER YOU GET EVERY TIME !
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