Section 4 of 5 · 3 puzzles
Quantitative Reasoning practice
Quantitative Reasoning uses number series instead of shapes. You see five or six numbers that follow a rule and pick the next one. The arithmetic is simple. Finding the rule is the puzzle.
Ready for the real thing? The full test has 25 fresh puzzles across all five sections.
What this section measures
Number series test the same skill as shape sequences, applied to quantities: find the rule, check it holds, apply it once more. They are the one part of the test that relies on learned arithmetic, so the numbers are kept small. The guide to pattern recognition covers how both kinds of sequence work.
Try it
- A94
- B95
- C71
- D96
- E93
- F70
Show the solution
The answer is B: 95.
- Try a single operation. Adding a fixed amount fails: 2 to 5 is +3, but 5 to 11 is +6. Multiplying by a fixed amount fails too: 2 × 2 is 4, not 5.
- Write the differences. 5 − 2 = 3, 11 − 5 = 6, 23 − 11 = 12, 47 − 23 = 24. The differences double each time: 3, 6, 12, 24. The next difference is 48, and 47 + 48 = 95.
- Confirm with a second view. Each term is double the previous one plus 1: 2 × 2 + 1 = 5, 5 × 2 + 1 = 11, 11 × 2 + 1 = 23, 23 × 2 + 1 = 47, and 47 × 2 + 1 = 95. Two methods, one answer.
- See the traps. 94 doubles but forgets the +1. 96 adds 2 instead of 1. 71 repeats the last difference (+24) instead of doubling it. 70 and 93 are near misses from slips in the arithmetic.
When a series grows faster and faster, the differences are usually the quickest way in. When it alternates up and down, try splitting it into two series: every other term.
What changes on the real test
The first number series uses a single operation. Later ones combine two operations, like this example, or interleave two separate series. Numbers stay below a few hundred, and there are six options for each.
Next, try a figure analogy.