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A. Multiplying by 1111 is very similar to multiplying by 111 except you will be adding 4 digits at a time instead of 3. See the Ex [1] below for an illustration:
Ex [1] 3414 x 1111 =_________.
a) Write down 4.
4
|
3 4 1 4
b) 1 + 4 = 5. Write down 5.
5
__|__
3 4 1 4
c) 4 + 1 + 4 = 9. Write down 9.
9
_____|_____
3 4 1 4
d) 3 + 4 + 1 + 4 = 12. Write down 2, carry *1.
12
________|_________
3 4 1 4
e) 3 + 4 + 1 = 8 + *1 = 9. Write down 9.
8+*1
_____|_____
3 4 1 4
f) 3 + 4 = 7. Write down 7.
7
__|__
3 4 1 4
g) Write down 3.
3
|
3 4 1 4
h) The answer is 3792954.
Ex [2] 124 x 1111 =_________.
a) When multiplying by 1111, you must multiply a 4-digit number for this method to work, so think of 124 as being 0124.
b) Write down 4.
c) 2 + 4 = 6. Write down 6.
d) 1 + 2 + 4 = 7. Write down 7.
e) 0 + 1 + 2 + 4 = 7. Write down 7.
f) 0 + 1 + 2 = 3. Write down 3.
g) 0 + 1 = 1. Write down 1.
h) Since we do not write 0 at the beginning of numbers the final answer is 137764.