Page 145 - NUMINO Challenge_C2
P. 145
Answer
Key
Problem solving Type 3-2 Applications of Divisibility Rules p.28~p.29
1 To be divisible by 5, the digit in the ones must 1 3 bars of soaps 12 months 36 bars of soaps
be 0 or 5. Also, the number that is divisible by 2 2 A number is a multiple of 4 if the last two digits
should have 0, 2, or 4 in the ones place. of the number is a multiple of 4 or 00.
Therefore, the digit in the ones place that Therefore, the digits that can go in the are 0,
satisfies the conditions is 0. 2, 4, 6, and 8.
If the 0 is divisible by 3, the numbers in the
3 Since 1 7 2 0 10, must be 8 to make
is be a multiple of 3. Therefore, they can the sum of the digits a multiple of 9.
be 12, 15, 21, 42, 45, 51, or 54.
120, 150, 210, 240, 420, 450, 510, 540 4 If 13,7 6 is a multiple of 36, then it is also a
multiple of both 4 and 9. Since 6 should be a
There are 8 numbers in total. multiple of 4, can be 1, 3, 5, 7, or 9. Among
these digits, 1 is needed to make the sum of the
2 Since the number is divisible by 5, can either digits of the store points a multiple of 9.
Therefore, 13,716 36 381 points are needed
be 0 or 5. 2350 10 must be to buy 1 bar of soap.
When 0,
divisible by 9 to make 2,350 divisible by 9.
Therefore, is 8.
When 5, 2 3 5 5 15 must be
divisible by 9 to make 2,355 divisible by 9. Problem solving
Therefore, is 3.
8 and 0, or 3 and 5 1 Since the sum of the store points is a multiple of
12, it is also a multiple of both 3 and 4.
0 should be a multiple of 4; therefore, can
be 0, 4, or 8 and since the sum of the digits is
7560 18, then to be a multiple of
3, should be 0, 3, 6, or 9. Since 0 satisfies the
two conditions above, is 0.
2 6,93 is a multiple of 72, it is also a multiple
of both 8 and 9. Since the last three digits, 93 ,
is a multiple of 8, the ones digit is 6. Also, since
the sum of the digits is a multiple of 9, 6
936 24; therefore, 3.
Since 36,936 points are used to buy 72
notebooks, you need 36,936 72 513 points
to buy a notebook.
NUMINO Challenge C2
Key
Problem solving Type 3-2 Applications of Divisibility Rules p.28~p.29
1 To be divisible by 5, the digit in the ones must 1 3 bars of soaps 12 months 36 bars of soaps
be 0 or 5. Also, the number that is divisible by 2 2 A number is a multiple of 4 if the last two digits
should have 0, 2, or 4 in the ones place. of the number is a multiple of 4 or 00.
Therefore, the digit in the ones place that Therefore, the digits that can go in the are 0,
satisfies the conditions is 0. 2, 4, 6, and 8.
If the 0 is divisible by 3, the numbers in the
3 Since 1 7 2 0 10, must be 8 to make
is be a multiple of 3. Therefore, they can the sum of the digits a multiple of 9.
be 12, 15, 21, 42, 45, 51, or 54.
120, 150, 210, 240, 420, 450, 510, 540 4 If 13,7 6 is a multiple of 36, then it is also a
multiple of both 4 and 9. Since 6 should be a
There are 8 numbers in total. multiple of 4, can be 1, 3, 5, 7, or 9. Among
these digits, 1 is needed to make the sum of the
2 Since the number is divisible by 5, can either digits of the store points a multiple of 9.
Therefore, 13,716 36 381 points are needed
be 0 or 5. 2350 10 must be to buy 1 bar of soap.
When 0,
divisible by 9 to make 2,350 divisible by 9.
Therefore, is 8.
When 5, 2 3 5 5 15 must be
divisible by 9 to make 2,355 divisible by 9. Problem solving
Therefore, is 3.
8 and 0, or 3 and 5 1 Since the sum of the store points is a multiple of
12, it is also a multiple of both 3 and 4.
0 should be a multiple of 4; therefore, can
be 0, 4, or 8 and since the sum of the digits is
7560 18, then to be a multiple of
3, should be 0, 3, 6, or 9. Since 0 satisfies the
two conditions above, is 0.
2 6,93 is a multiple of 72, it is also a multiple
of both 8 and 9. Since the last three digits, 93 ,
is a multiple of 8, the ones digit is 6. Also, since
the sum of the digits is a multiple of 9, 6
936 24; therefore, 3.
Since 36,936 points are used to buy 72
notebooks, you need 36,936 72 513 points
to buy a notebook.
NUMINO Challenge C2
