"NeoVikesTX" wrote:
"smootpepper" wrote:
How about

1 = $1
1 = $2
1 = $4
1 = $8
1 = $10
1 = $25
1 = 50

7 total.
The correct answer is 7 envelopes.

It can also be done this way, which is the way we were shown.

1
2
4
8
16
32
37

=7 envelopes.

The first 6 numbers are in sequence with a common ratio of 2 (or geometric progression). The last number, 37, is found by adding up the first 6 numbers and subtracting it by 100.

Both answers seem to work out ok.
What about the coin change?