This post is about 3digit by 3 digit multiplication. For 2 by 3 digit, append zero in hundreds place to convert to 3 digit
Example
387
x 542
----------
Step 1:
Units place vertically - write answer as in last post
387 * * *
|
x 542 * * *
---------- 7x2=14, 4 in place, 1 lower for carry
14
Example
387
x 542
----------
Step 1:
Units place vertically - write answer as in last post
387 * * *
|
x 542 * * *
---------- 7x2=14, 4 in place, 1 lower for carry
14
Step 2:
Units and tens place crosswise plus old carry - write answer as in last post
387 * * *
X
x 542 * * *
---------- (8x2)+(7x4)+(1old carry)=45; write as 45
454
Step 3:
Units tens and hundred's place starwise plus old carry - write answer as in last step
387 * * *
*
x 542 * * *
---------- ( 3x2)+(8x4)+(7x5)+(4previous carry)=77
7754
Step 4:
Only tens and hundred's place crosswise plus old carry - write answer as in last step
387 * * *
X
x 542 * * *
---------- (3x4)+(8x5)+(7previous carry)=59write answer as in last step
59754
Step 5:
Only Hundreds place vertically
387 * * *
|
x 542 * * *
---------- (3x5)+5 previous carry, final answer.
209754
See figure
Units and tens place crosswise plus old carry - write answer as in last post
387 * * *
X
x 542 * * *
---------- (8x2)+(7x4)+(1old carry)=45; write as 45
454
Step 3:
Units tens and hundred's place starwise plus old carry - write answer as in last step
387 * * *
*
x 542 * * *
---------- ( 3x2)+(8x4)+(7x5)+(4previous carry)=77
7754
Step 4:
Only tens and hundred's place crosswise plus old carry - write answer as in last step
387 * * *
X
x 542 * * *
---------- (3x4)+(8x5)+(7previous carry)=59write answer as in last step
59754
Step 5:
Only Hundreds place vertically
387 * * *
|
x 542 * * *
---------- (3x5)+5 previous carry, final answer.
209754
See figure