10
209 228 247 266 285 304 323 342 361 380 399
The multiples of seven that are between 200 and 400 are: 203, 210, 217, 224, 231, 238, 245, 252, 259, 266, 273, 280, 287, 294, 301, 308, 315, 322, 329, 336, 343, 350, 357, 364, 371, 378, 385, 392, 399.
400 / 7 = 57, so there are 57 multiples of 7 under 400.
110
9
10
400, 600
The multiples of 7 between 200 and 400 are: 203, 210, 217, 224, 231, 238, 245, 252, 259, 266, 273, 280, 287, 294, 301, 308, 315, 322, 329, 336, 343, 350, 357, 364, 371, 378, 385, 392, 399. The sum of all the multiples of 7 between 200 and 400 is 8,729.
32 of them.
400, 600, 800.
They are: 200, 400, 600, 800 and 1,000
200, 400, 600, 800, etc. take any natural number n- 1,2,3,4 , ... and multiply it by 200 and that is a multiple of 200 There are infinitely many of them.
200, 400, 600, 800, 1000, 1200
There are 57 such numbers.
200 years.
200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, 2000, . . .