Hey there!
You can count from 668 to 900 using the following:
668 → 768 → 868 (two 100s)
868 → 878 → 888 → 898 (three 10s)
898 → 899 → 900 (two 1s)
Hope this helped you out! :-)
Seven has the greatest value as a digit, but 1, 000 has the greatest standard form value.
49: 1 7, 49
84: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
The GCF is 7