A number × 1.5 is equal to half of the number itself

A number × 1.1 is equal to the misplaced addition of this number

A number × 0.9 is equal to the misalignment of this number.

A number ÷5 is equal to this number × 2, with the decimal point moved one place

A number ÷25 is equal to this number × 4, with the decimal point moved two places

A number ÷125 is equal to this number × 8, with the decimal point moved three places

Must memorize

Adding and subtracting two-digit numbers: verbal arithmetic

Add more than three digits: use less pen

Start counting from the high position on the left, and proceed directly to one digit after the calculation.

1. Critical value: (insert critical value)

2. Ordinary numerical values ​​(underline method, based on the premise of easy calculation and less borrowing)

Two digits × single digits: convert multiplication into addition

Two digits × two digits: convert multiplication into addition

Hundred points: according to the difference between options