This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Sunday, August 22, 2010

RGS Primary 2009 PSLE Math Prelim Paper 2 Q14

John shifted the decimal point of a number twice to the left to obtain a new number. The difference between the new number and the original number was 136.62.
a) How many times the new number is the original number?
b) What is the sum of the 2 numbers?

Solution

a)
Answer: 100 times


b)
Original number --> 1 unit
New number --> 100 units

100 units - 1 unit --> 136.62
99 units --> 136.62
1 unit --> 136.62 divided by 99 = 1.38

Sum of the two numbers
--> 100 units + 1 unit = 101 units

101 units --> 101 x 1.38 = 139.38

Answer: 139.38

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