Part ACSIR NET December 2025match-the-residue-class-mod-3-not-the-nearer-looking-index

Match the residue class mod 3 not the nearer looking index

Suppose $a_{1}, a_{2}, \dots, a_{300}$ are integers such that $a_{i}$ ₋ $_{1} + a_{i} + a_{i}$ ₊ $_{1} = 2025$ for all i = 2, 3, …, 299. If $a_{7} = -5, a_{9} = 37$ , then the value of $a_{106}$ is

A.1993
B.37
C.−5✓ Correct
D.2030

You have the answer. Trap Analysis is why the other three were written.

Not a worked solution repeated four times — the specific reasoning error each wrong option was built to reward, and why this one tests execution slip.

See pricing

50 are analysed free — try those first.

The trap it tests

Execution slip

The idea was right. The computation was not.

Drill statements like this

Last revised 12 Sept 2026. Found a mistake? Tell us — corrections are the fastest thing we act on.

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