Question 1127640
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There is no magic formula for answering a question like this.  You simply need to look at each number from 60 to 100 and see if you can make each one with the given ground rules.<br>
Start with 60; and always use the largest numbers you can.  Here's the start:<br>
Until you get to 68, the largest numbers you can use are 37 and 20.  Since 37+20=57, you can find...<br>
60 = 37+20+3
61 = 37+20+3+1  (1 more than 60; add the 1}
62 = 37+30+3+2  (1 more than 61; replace the 1 with 2)
63 = 37+30+6    (1 more than 62; replace the 3+2 with 6)
64 = ....<br>
You need to see if you can make all the other numbers up through 67 with the given ground rules.<br>
Then when you get to 68 it gets a bit easier for a while.<br>
68 = 68
69 = 68+1
70 = 68+2
71 = ...<br>
You can see that each time you get to a number that can be made with either one or two of the given numbers, you will be able to get the next several using the 1, 2, 3, and 6.<br>
So you will be able to get the next several numbers after 68+11=79, and the next several after 68+20 = 88.<br>
I leave it to you to do the rest of the work.<br>
There are only two numbers from 60 to 100 that you can NOT make with the given ground rules; I'll let you find them.