Basic Simplification Quiz Set 004

Had he attempted all correctly, he would have got 94 × 4 = 376. But he has lost 376 - 141 = 235 marks due to wrong attempts. Each wrong attempt leads to an overall loss of 5 marks, so the number of wrong attempts is 235/5 = 47.

This is a multiplication by 9. Proceed like this: 183 × 9 = 183 × (10 - 1) = 183 × 10 - 183 = 1830 - 183 = 1647. Sometimes, the options can be ruled out by examining the units places, but for simpler cases these shortcuts will help you save time overall.

This is a multiplication by a power of 5. The best way is to observe that 25 = 5². There are 2 powers of 5. So append 2 zeroes and divide by 2², like this: $13900/4$ = 3475.

Let x be the number of dogs, and y the number of hens. Total number of legs = 4x + 2y. The total number of heads is x + y. So 4x + 2y = 2(x + y) + 26. Cancelling 2y, and solving for x, we get x = 13.

We have -261 + (-380) - (-521) + 105 = -261 - 380 + 521 + 105 = -(261 + 380) + (521 + 105) = -641 + 626 = -15.