Page 173 - NUMINO_WB_5B

091-S1-1

1. Look at the diagrams and answer the questions.

What is the last digit of the 20th number when multiplying 0.2 twenty times?

0.2 0.2 The last digit of the products are repeated
0.2 0.2 0.04 in the order of 2, 4, 8, 6.
0.2 0.2 0.2 0.008 Also, multiplying 0.2 twice gives a second
0.2 0.2 0.2 0.2 0.0016 decimal place product and multiplying it
0.2 0.2 0.2 0.2 0.2 0.00032 three times gives a product that is a third
0.2 0.2 0.2 0.2 0.2 0.2 0.000064 decimal place number.
Therefore, multiplying 0.2 twenty times will
give a product that is a twentieth decimal
place number.

Therefore, find the last digit of the 20th
number, 20 4 5. So, the number is 6.

What is the last digit number of the 30th number when multiplying 0.7 thirty times?

0.7 0.7
0.7 0.7 0.49
0.7 0.7 0.7 0.343
0.7 0.7 0.7 0.7 0.2401
0.7 0.7 0.7 0.7 0.7 0.16807
0.7 0.7 0.7 0.7 0.7 0.7 0.117649