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secondary 4 | E Maths
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Keith Koh
Keith Koh

secondary 4 chevron_right E Maths chevron_right Singapore

Help please!

Date Posted: 4 years ago
Views: 325
J
J
4 years ago
Let the two digit number be AB, here A is the digit in the tens place and B is the digit in the ones place.

A + B = 11 (from question) ①


Value of the number AB

= 10 x A + 1 x B
= 10A + B

When reversed, the number becomes BA.

Value of the number BA
= 10 x B + 1 x A
= 10B + A


Since the result is 9 when new number is subtracted from the original,

Value of original - value of new number = 9

(10A + B) - (10B + A) = 9

9A - 9B = 9

A - B = 1

A = 1 + B ②

Sub ② into ①,

1 + B + B = 11

1 + 2B = 11

2B = 10

B = 5

So A = 1 + 5 = 6

The number is 56