5=3×2- 1
14=5×3- 1
55= 14×4- 1
274=55×5- 1
1643=274×6- 1
1 1550= 1643×7- 1
Fill in 1643
Fill in the blanks: 1.
Clockwork = 6 degrees per minute.
Minute hand per minute = 1/2 degrees.
Coincidence time =180 ÷ (6-1/2) = 360/11min.
Fill in the blanks: 2
208=2×2×2×2× 13, so 2 and 13 are prime factors of 208, so the sum of all prime factors of 208 is 2+ 13= 15.