Identify the roll number that doesn't fit this rule. Last 3 digits = First 3 digits + 100

Correct — D.
Rule: last three digits = first three digits + 100.

200 + 100 = 300, and 200K300 ends 300. Fits.
150 + 100 = 250, and 150K250 ends 250. Fits.
250 + 100 = 350, and 250K350 ends 350. Fits.
100 + 100 = 200, but 100K250 ends 250. Breaks.

The roll number that breaks the rule → option (d).

Why the others are wrong

• (a)
  200K300 — 200K300 follows the rule: the first three digits are 200, and 200 + 100 = 300, exactly the digits after the K.
• (b)
  150K250 — 150K250 follows the rule: 150 + 100 = 250, which matches its last three digits exactly.
• (c)
  250K350 — 250K350 follows the rule: 250 + 100 = 350, matching the digits after the K, so it is not the misfit.

A rule-check item hands you the rule and asks which case breaks it. Split each roll number at the letter K, apply the rule to the first three digits, and compare the result with the last three.

200K300, 150K250 and 250K350 all pass. 100K250 would need to end in 200, so it is the one that does not fit.

Key facts

• The rule reads Last 3 digits = First 3 digits + 100, and it ignores the letter in the middle.
• 100K250 ends 150 more than it starts, not 100 more.
• 200K300, 150K250 and 250K350 each end exactly 100 more than they start.

Common traps

• Applying the rule backwards, as First = Last + 100, which makes every option fail
• Stopping at the first option that fits instead of testing all four

No directly related past PYQ was found.