Multiple choice

Find the missing term in the following number series- 20 25 105 285 605 ?

  1. 1100

  2. 1205

  3. 1305

  4. 1105

  5. 1200
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pattern follows: (difference×2)+(previous number). Starting with 20 and 25 (diff=5): 25=20+5. Then 105=25×4+5 (diff=80). Then 285=105×2+75 (diff=180). Then 605=285×2+35 (diff=320). The next step: 605+500=1105. This can also be seen as differences increasing by 100: 5, 80, 180, 320, 500 (each adds 100 more than previous increment). So 605+500=1105, matching option D.

Keep practicing — related questions