Question

Третьеклассники выполняли сложение в суммах 230 + 60, 420 + 40, 510 + 70. Они рассуждали так: Лена: 230 + 60 = (200 + 30) + 60 = = 200 + (30 + 60) = 200 + 90 = 290 Олег: 230 + 60 = 23 десятка + 6 десятков = = 29 десятков = 290 2) Какой способ тебе нравится больше? Найди значения остальных сумм этим способом.

Answer 1

2) Второй способ
420+40= 42 десятка + 4 десятка = 46 десятков (=460)
510+70= 51 десяток + 7 десятков = 58 десятков (=580)

Answer 2

Addition by Regrouping Method

The third graders were performing addition using the regrouping method. Let's analyze the reasoning of Lena and Oleg:

1. Lena's Method: - Lena approached the addition problem by breaking down the numbers into hundreds and tens. She first added 200 and 30 to get 230, and then added 60 to get a final sum of 290. - Lena's method can be summarized as follows: - 230 + 60 = (200 + 30) + 60 = 200 + (30 + 60) = 200 + 90 = 290.

2. Oleg's Method: - Oleg used the regrouping method to add the numbers. He added the tens and then the hundreds separately. He added 23 tens and 6 tens to get 29 tens, which is equal to 290. - Oleg's method can be summarized as follows: - 230 + 60 = 23 tens + 6 tens = 29 tens = 290.

Both Lena and Oleg arrived at the same sum of 290 using different methods.

Now, let's find the values of the remaining sums using the same regrouping method:

1. 420 + 40: - Lena's method: 420 + 40 = (400 + 20) + 40 = 400 + (20 + 40) = 400 + 60 = 460. - Oleg's method: 420 + 40 = 42 tens + 4 tens = 46 tens = 460.

2. 510 + 70: - Lena's method: 510 + 70 = (500 + 10) + 70 = 500 + (10 + 70) = 500 + 80 = 580. - Oleg's method: 510 + 70 = 51 tens + 7 tens = 58 tens = 580.

Using the regrouping method, the values of the remaining sums are as follows:

1. 420 + 40 = 460. 2. 510 + 70 = 580.

The regrouping method allows for a systematic approach to addition, breaking down the numbers into place values and adding them accordingly. It is a useful method for performing addition with larger numbers.