A marker starts at 90 on a number line and jumps left. Its jumps are 1, 2, 3, 4, ... steps long (each jump one longer than the last). After how many jumps does it first reach 0 or go past it (to the left)?

Question

Accepted Answer

13. Sum 1+2+...+n must be at least 90. 1+...+12 = 78 (still at 12, not yet 90); 1+...+13 = 91, which is past 90, so after 13 jumps it is at 90 - 91 = below 0. The answer is 13.

A marker starts at 90 on a number line and jumps left.
Its jumps are 1, 2, 3, 4, ... steps long (each jump one longer than the last).
After how many jumps does it first reach 0 or go past it (to the left)?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 6 Number Line Operations practice

A marker starts at 90 on a number line and jumps left.Its jumps are 1, 2, 3, 4, ... steps long (each jump one longer than the last).After how many jumps does it first reach 0 or go past it (to the left)?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 6 Number Line Operations practice

A marker starts at 90 on a number line and jumps left.
Its jumps are 1, 2, 3, 4, ... steps long (each jump one longer than the last).
After how many jumps does it first reach 0 or go past it (to the left)?