What is longmult 20*15 ?

The solution to longmult 20*15 is 300

Evaluate 20*15

long multiplication

20 \cdot 15

300

Solution steps

20 \cdot 15

Line up the numbers

\times 2105

Multiply the top number by the bottom number one digit at a time starting with the ones digit (from right to left)

Multiply the top number by the bolded digit of the bottom number

\times 2105

Mutliply the bold numbers:

0 \cdot 5 = 0

\frac{\times 2 1 0 5}{0}

Mutliply the bold numbers:

2 \cdot 5 = 10

Carry

1

to the column on the left and write

0

in the result line

\frac{\times 1 2 1 0 5}{0 0}

Add the carried digit,

1

, to the result

\frac{\times 1 2 1 0 5}{1 0 0}

Multiply the top number by the bolded digit of the bottom number

\frac{\times 2 1 0 5}{1 0 0}

Mutliply the bold numbers:

0 \cdot 1 = 0

\frac{\times 2 1 0 5}{1 0 0 0}

Mutliply the bold numbers:

2 \cdot 1 = 2

\frac{\times 2 1 0 5}{1 2 0 0 0}

Add the rows to get the answer. For simplicity, fill in trailing zeros

\frac{\times 2 1 0 5}{1 2 0 0 0 0}

100 + 200 = 300

+ 120000

Add the digits of the bolded column:

0 + 0 = 0

\frac{+ 1 2 0 0 0 0}{+ 0}

Add the digits of the bolded column:

0 + 0 = 0

\frac{+ 1 2 0 0 0 0}{+ 0 0}

Add the digits of the bolded column:

1 + 2 = 3

\frac{+ 1 2 0 0 0 0}{+ 3 0 0}

= 300

= 300