A summary of commonly used math application formulas in the first volume of third-grade elementary school to provide children with learning

Summary of commonly used application problem formulas in third grade mathematics volume 1. Formulas for sum and difference problems (sum + difference) ÷ 2 = large number (sum and difference) ÷ 2 = decimal two, formulas for sum and multiple problems and ÷ (multiple – 1) = decimal decimal × multiple = large number or (and decimal = large number) 3. The formula for the difference problem difference ÷ (multiple – 1) = decimal decimal × multiple = large number or (decimal + difference = large number) 4. Formula for the tree planting problem 1. The tree planting problem on the non-closed line can be mainly divided into the following three situations: 1.1. If trees are to be planted at both ends of the non-closed line, then: number of plants = number of sections + 1 = total length ÷ spacing between trees – 1 Full length = plant spacing × (number of plants – 1) plant spacing = full length ÷ (number of plants – 1) 1.2. If trees are to be planted at one end of the non-closed line and not at the other end, then: number of plants = number of sections = full length ÷ total length of plant spacing = Plant spacing × number of plants Plant spacing = full length ÷ number of plants 1.3. If no trees are planted at both ends of the non-closed line, then: number of plants = number of segments – 1 = full length ÷ plant spacing – 1 Full length = plant spacing × (number of plants + 1) plant spacing = full Length ÷ (number of plants + 1) 2. The quantitative relationship of tree planting problems on closed lines is as follows: number of plants = number of sections = full length ÷ spacing between plants total length = spacing between plants × number of plants spacing between plants = full length ÷ number of plants 5. The formula for the profit and loss problem (profit + loss ) ÷ the difference between the two distribution amounts = the number of shares participating in the distribution (big profit and small profit) ÷ the difference between the two distribution amounts = the number of shares participating in the distribution (big loss and small loss) ÷ the difference between the two distribution amounts = participation Number of assigned shares 6. Formula for encounter problem Encounter distance = Speed ​​sum =Catching distance ÷Speed ​​difference Speed ​​difference =Catching distance ÷Catching time 8. Water flow problem Downstream speed = Still water speed + Water flow speed Countercurrent speed = Still water speed – Water flow speed Stilling water speed = (Downstream speed + Countercurrent speed) ÷ 2 Water flow speed = (cocurrent speed – countercurrent speed) ÷2