Click on the option you think is right and then check by clicking on the Show Answer button. You can change your option as many times as you like.
Some equations are solved on the basis of certain system. Find out the correct answer for the unsolved equation on that basis.
1. If 12 x 7 = 408 and 9 x 8 = 207 then 13 x 7 = ?
190
91
901
109
Answer (d). 12 x 7 = 84 therefore it is represented in reverse order by adding a 0 in between. Similarly 9 x 8 = 72 = 207 and 13 x 7 = 91 = 109.
2. a = 11 (242) 121 ; b = 14 (392) 196 ; c = 13 (?) 169
182
338
2197
28224
Answer (b). 242 = 11² x 2;, 392 = 14² x 2; and therefore 13² x 2 = 338.
3. 323 x 41 = 14323, 137 x 72 = 27731, 48 x 87 = 7884, 34 x 75 = ?
2550
5743
7534
4357
Answer (b). The numbers are obtained by just placing them in reverse order from equation to solution. 323 x 41 is written in reverse order to get 14323. Similarly 137 x 72 = 27731.
4. 11 x 12 x 13 = 234, 24 x 23 x 35 = 658, 31 x 43 x 54 = ?
497
974
749
479
Answer (d). The first equation is solved by adding the digits of every number 11 = 2(1+1) 12 = 3(1+2) and 13 = 4(1+3) which gave 234. Similarly 2 + 4 = 6, 2 + 3 = 5 and 3 + 5 = 8. Thus 3 + 1 = 4, 4 + 3 = 7 and 5 + 4 = 9. The answer is 479.
5. 16 (210) 14, 14 (156) 12, 12 (?) 10
110
100
120
90
Answer (a). First equation is 16, 210 = 15² - 15 and 14. And second equation is 14, 13² - 13 and 12. Similarly the solution is 12, 11² - 11 and 10.
6. A = 3(21)247, B = 5(-)407, C = 7(49)567
28
25
35
38
Answer (c). The last digit of first equation that is 7 multiplied by first digit 3 gives 21 which is in brackets. Then the sum of 3 and 21 gives you 24 which is placed before 7. So is the solution for the third equation 7 x 7 = 49 + 7 = 56. Therefore the answer is 7 x 5 = 35.
7. 7 x 5 x 4 = 57354, 8 x 7 x 3 = 78563, then 6 x 8 x 5 = ?
86585
86855
68485
86485
Answer (d). Here first two digits in the equation are multiplied (7x5) to arrive at the middle number(35) and last digit is kept as it is. Then first two digits are reversed. Similarly, 8 x 7 = 56, 3 is taken as it was in the last place and first two digits (8 and 7) are reversed to get 78 - 56 - 3. Similarly 6 x 8 = 48 and first two digits 6 x 8 are taken as 86 - 48 - 5.
8. If 14 x 13 = 128 and 16 x 13 = 280 then 15 x 11 = ?
516
156
165
615
Answer (b). The product of 14 x 13 = 182 and 16 x 13 = 208. It can be seen that the last two digits have been reversed to get the answer. Since 15 x 11 = 165, the answer is 156.
9. If 264 * 2 = 6, 870 * 3 = 5, then what should be 735 * 5 be equal to
Answer (a). The first digit of the answer is the difference of two digits in the question and the second digit is the sum of two digits. Thus, 7 - 2 = 5 and 7 + 2 = 9 and the answer is 59. Therefore, 5 - 4 = 1 and 5 + 4 = 9 and the answer is 19.
19. If 8 x 2 = 61 : 8 x 5 = 04, what is 8 x 10 = ?
80
08
81
18
Answer (b).
20. 27(18)3; 216(180)6; 729(?)9
810
700
81
648
Answer (d). The number in brackets is the difference of the first number and the square of the second number outside the brackets. 27 - 32 = 18; 216 - 362 = 180. Thus 729 - 92 = 648.
