Answer:
21, 42, 63, 84
Step-by-step explanation:
Numbers that have a star and a circle on them are all multiples of 3 and 7. As there are less multiples of 7 between 1-100 we should list the multiples of 7 and then check if they are also multiples of 3.
7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, 91, 98
A quick way of calculating if a number is a multiple of 3 is to see if its digital root is either 3, 6, or 9
7 is not as 7 is not a multiple of 3
14 is not as 1+4 = 5 is not a multiple of 3
21 is, as 2+1 = 3 is a multiple of 3
28 is not, as 2+8 = 10 is not a multiple of 3
35 not, 3+5=8
42 is, 4+2=6
49 is not, 4+9=13
56 is not , 5+6=11
63 is, 6+3=9
70 is not, 7+0=7
77 is not, 7+7=14, 1+4=5
84 is, 8+4=12, 1+2=3
91 is not, 9+1=10 1+0 = 1
98 is not, 9+8=17, 1+7=8
