7.816×1.45+3.14×2.184+1.69×7.816=7.816×1.45+1.69×7.816+3.14×2.184=7.816×（1.45+1.69）+3.14×2.184=7.816×3.14+3.14×2.184=3.14×（7.816+2.184）=3.14×10=31.4；故答案为31.4．