The algorithm of multiplying two-digit speed by two-digit speed is: head times head, tail adds tail, tail multiplies tail, after a head adds 1, head times head, tail multiplies tail, heads are complementary, tails are the same, after a head adds 1, head times head and tail times tail. The above four are fast algorithms for multiplying two digits: head by head, tail by tail, and tail by tail. These algorithms can also be used directly at any time.

The speed algorithm is

Quick calculation is one of the mathematical calculation methods. Fast calculation refers to the fast operation of addition, subtraction, multiplication and division by using the special relationship between numbers, and the fast calculation method of adding, subtracting, multiplying and dividing any number quickly and accurately with one thought and one method. This operation method is called speed algorithm and heartbeat algorithm. The quick calculation methods include whole brain quick calculation and Wei's quick addition, subtraction, multiplication and division by using the special relationship between numbers.

Concept, a mathematical calculation method, enables learners to quickly and accurately master the fast calculation method of addition, subtraction, multiplication and division of any number in a short time with an idea and a method without any calculation tools. So as to quickly improve learners' quick calculation ability in oral and mental arithmetic.