Multiplication Tricks
25 x 63
1575
63 divided by 4 = 15 r3
3 x 35 = 75
so 1575 is the answer
5/12 + 3/12
2/3
round to unit
687.84
688
70341 divided by 9
6
7+0+3+4+1 = 15
1+5 = 6
add up all digits
keep doing so until you only have one digit
that is your remainder, unless it is 9. if that happens the remainder is 0
Perimeter of rectangle with sides 4ft and 6ft
20 ft
125 x 88
11000
divide the number by 8
add 3 zeros
CMXXXIX converts to what Arabic number
939
50 x 189
9450
189 divided by 2 = 94 r1
1 x 50 = 50
9450
4/25 divided by 3
4/75
round to the nearest thousandths place 56701.86287
56701.863
67027 divided by 5
2
look at the last digit
0 to 4 = remainder is that digit
5 = remainder is 0
6-9 = remainder is subtract it from 5 and then that is the remainder
What is the area of a triangle with a base of 5inch and a height of 3 inches
7.5 inches
101 x 56
5656
LXXXVIII converts to what Arabic number?
88
75 x 24
1800
The trick is for multiplying by 75
24 x 3 = 72
72 divided by 4 =18
add two zeros to the end
1800
7 2/5 % equals what as a fraction
74/1000 simplified to 37/500
Round to the hundreds place
7846.827
7800
76438 divided by 2
0
if the number is even, remainder is 0
if the number is odd, remainder is 1
What is the semi-perimeter of a triangle with sides 10in, 12 in and 14 inch
Semi Perimeter = 18in
673 x 101
67973
add the three digit number to the hundreds digit
673 + 6 = 679
CMXXXVll converts to what Arabic number?
937
643 x 11
7073
keep ones digit
Add two digits from right to left
Regroup as needed
Add a zero in front of the digit to the furthest left
3 1/4 x 3 3/4
12 3/16
What digit is in the tenths place?
745.920
9
16493 divided by 4
1
Use the last two digits
Divide those by 4 - 93 divided by 4 = 23 r1
The remainder of that is the remainder for the whole number
What is the area of a triangle with a hypotenuse of 5inch and leg of 4 inches.
6 (double check me on this one)
345 x 103
345,000
34
4701 x 12
56412
double the ones place and write it down
then double the next digit and add to the previous digit.
regroup as needed
add a zero -furthest left
5 1/3 x 7 1/3
39 1/9
What number is represented in expanded notation
6 x 104 + 9 x 102 + 2 x 100 + 5 x 10-3
60,902.005
36812 divided by 3
2
3 + 6 +8 + 1 + 2 =20
20 divided by 3 is 6 with a remainder of 2
What is the perimeter of a rhombus whose side is 16 1/4 inches
65 inches
7.89 divided by 102
.0789
DCCCLXXV + 125 equals what (answer in Arabic digits)
1000