Finally, add up the results and the result is: 4200.
Reflections on solving problems in vertical calculation;
1. Align the last digit of the two multipliers first.
2. Then use the second multipliers respectively, and multiply each bit with one multiplier in turn, starting from the last bit.
3. Finally, the calculation results are accumulated into products.
4. If the multiplier is decimal, you can expand the corresponding multiple first, and then reduce the product by the corresponding multiple.