1.3.10 Combination of Tricks

The following are a practice set of combination of some of the multiplication tricks already mentioned in the book. Most are approximations which occur on the third or fourth columns of the test.

Problem Set 1.3.10

12×14×1612 \times 14 \times 16 *
21×31×4121 \times 31 \times 41 *
13×15×1713 \times 15 \times 17 *
14×16×2814 \times 16 \times 28 *
146×5×154146 \times 5 \times 154 *
24×34×4424 \times 34 \times 44 *
24×36×4824 \times 36 \times 48 *
44×25×11244 \times 25 \times 11^2 *
22×25×2822 \times 25 \times 28 *
83×87×9183 \times 87 \times 91 *
43×47×5143 \times 47 \times 51 *
27×29×31×3327 \times 29 \times 31 \times 33 *
23×33×4323 \times 33 \times 43 *
29×127+31×21329 \times 127 + 31 \times 213 *
41×44×4741 \times 44 \times 47 *
31×42×5331 \times 42 \times 53 *
22×44×6622 \times 44 \times 66 *
39×40×4139 \times 40 \times 41 *
13293×171×15\sqrt[3]{1329} \times \sqrt{171} \times 15 *
42×48×4542 \times 48 \times 45 *
52×55×5852 \times 55 \times 58 *
18×20×2218 \times 20 \times 22 *
24×34×4424 \times 34 \times 44 *
80×82×8480 \times 82 \times 84 *
28×30×3228 \times 30 \times 32 *
66×68×7066 \times 68 \times 70 *
63×65×6763 \times 65 \times 67 *
41×43÷51×5341 \times 43 \div 51 \times 53 *
67×56+65×7667 \times 56 + 65 \times 76 *
56×45+54×6556 \times 45 + 54 \times 65 *
112×123+132×12111^2 \times 12^3 + 13^2 \times 121 *
29×11+31×10929 \times 11 + 31 \times 109 *
752÷252×50475^2 \div 25^2 \times 50^4 *
183×153÷9318^3 \times 15^3 \div 9^3 *
505÷255×5550^5 \div 25^5 \times 5^5 *
243×213÷4424^3 \times 21^3 \div 4^4 *
213×182÷9321^3 \times 18^2 \div 9^3 *
754÷503×25275^4 \div 50^3 \times 25^2 *
242×183÷6424^2 \times 18^3 \div 6^4
33803×223×16\sqrt[3]{3380} \times \sqrt{223} \times 16 *