9

7

8

×8+8

6

7

×7+7

5

6

×6+6

4

5

×5．9

7

8

×8+8

6

7

×7+7

5

6

×6+6

4

5

×5
=（9+

7

8

）×8+（8+

6

7

）×7+（7+

5

6

）×6+（6+

4

5

）×5
=72+7+56+6+42+5+30+4
=222．