Start here · the first lesson of Number analogy
Number analogy
Analogy, Classification and Word Order · for IPMAT Indore, IPMAT Rohtak and JIPMAT
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The idea
A number analogy states a rule through one pair (or two) and asks for the number the same rule gives. JIPMAT 2021 set two: 210 : 380 :: 182 : ? and a number-set item. The rule is almost always one of a short list of operations on the whole number or on its digits.
Textbook vs exam method
Textbook method
Write the first pair as an expression in the first number: test multiples, powers, powers ± the number, products of neighbours, digit sums and products. Confirm on the second pair, then apply.
Exam method
- Look at the size jump. About × 5 to × 10: a product with a small factor or . About : a square ± a little. Far larger: a cube or a factorial.
- Factorise the larger number. 1716 = 11 × 12 × 13 tells you the rule at once (12 → 1716, so 17 → 16 × 17 × 18 = 4896).
- If the number is small and the other large, try the digits. 429 → (4 + 2 + 9)² = 225.
- Number sets. divide by the common factor and compare the pattern left over.