0 2 5 x 1 ----- 5 | write the number. You should always write your answers thusly so that errors which may occur in your work may be quickly found. If you are writing on paper it is preferable that you use a pencil and graph paper, writing one digit in every-other square. |
0 2 5 x 1 ----- 2 5 | write the number. |
0 2 5 x 1 ----- 0 2 5 | writing the number from under the zero position will keep you in good practice for later lessons. |
0 4 2 5 x 10 ------- 0 | remember that the "neighbour" when one is looking at far right digit of the multiplicand is not "nothing", but rather is considered to be an unwritten zero. |
0 4 2 5 x 10 ------- 5 0 | write the neighbour. |
0 4 2 5 x 10 ------- 2 5 0 | write the neighbour. |
0 4 2 5 x 10 ------- 4 2 5 0 | write the neighbour. |
0 7 5 6 3 2 x 11 ----------- 2 |
see the 2, say [ 2 ], add the neighbour (zero).
Your mental stops should have been: [ 2 ] answer: 2. |
0 7 5 6 3 2 x 11 ----------- 5 2 |
see the 3, say [ 3 ], add the neighbour (2) and
say [ 5 ].
Your mental stops should have been: [ 2, 5 ] answer: 5. |
0 7 5 6 3 2 x 11 ----------- 9 5 2 |
see the 6, say [ 6 ], add the neighbour (3) and
say [ 9 ].
Your mental stops should have been: [ 6, 9 ] answer: 9. |
0 7 5 6 3 2 x 11 ----------- `1 9 5 2 |
see and say [ 5 ], add the neighbour (6) and
say [ 11 ]. Carry the one.
Your mental stops should have been: [ 5, 11 ] answer: 11. Notice how easy it is to not only write but also to remember the carry when using this style of writing out the problem with spaces between the numbers. |
0 7 5 6 3 2 x 11 ----------- `3`1 9 5 2 |
see the carry and the 7, and say [ 8 ], add the
neighbour (5) and say [ 13 ]. Carry the one.
Your mental stops should have been: [ 8, 13 ] answer: 13. |
0 7 5 6 3 2 x 11 ----------- 8`3`1 9 5 2 |
see the carry and the zero, and say [ 1 ], add
the neighbour (7) and say [ 8 ].
Your mental stops should have been: [ 1, 8 ] answer: 8. |
Once again I have provided a sample problem, this time to illustrate the proper mental method with regards to the carry. Try 984 times 2.
0 9 8 4 x 2 ------- 8 | double the number. |
0 9 8 4 x 2 ------- `6 8 | double the number. |
0 9 8 4 x 2 ------- `9`6 8 | double the number and add the carry. Do not say [ 9, 18, 19 ]; see the carry mark and say [ 9, 19 ], or as you become better at this form of doubling, simply [ 19 ]. |
0 9 8 4 x 2 ------- 1`9`6 8 | double the number (zero) and add the carry. |
0 2 5 2 x 12 ------- 4 |
see the number (2) and say its double [ 4 ], and add
the neighbour (zero).
Your mental stops should have been: [ 4 ] answer: 4. |
0 2 5 2 x 12 ------- `2 4 |
see the 5 and say its double [ 10 ], then add the 2
and say [ 12 ]. Carry the one.
Your mental stops should have been: [ 10, 12 ] answer: 12. |
0 2 5 2 x 12 ------- `0`2 4 |
see the 2 and the carry, say [ 5 ], then add the 5
and say [ 10 ]. Carry the one.
Your mental stops should have been: [ 5, 10 ] answer: 10. |
0 2 5 2 x 12 ------- 3`0`2 4 |
see the zero and the carry, say [ 1 ], then add the 2
and say [ 3 ].
Your mental stops should have been: [ 1, 3 ] answer: 3. |
2 5 | 3 8 | 5 3 | 6 9 | 5 1 | 4 8 |
9 6 | 1 2 | 4 0 | 9 5 | 8 6 | 5 4 |
2 6 | 8 9 | 7 4 | 3 1 | 6 3 | 5 8 |
3 5 | 1 6 | 6 5 | 9 4 | 5 2 | 3 6 |
Finally, using the same set of numbers, practice seeing and doubling the number, and adding the neighbour... which is, as you know, how you multiply by twelve.
enjoy...