Just started learning linear regression, started with a simple perfect linear regression example, X values are 1,2,3,4,5 and Y values are 1,2,3,4,5. And this is the summary I am getting: Residuals: 1 2 3 4 5 -4.828e-16 8.351e-16 -2.098e-16 -1.544e-16 1.196e-17 Coefficients: Estimate Std. Error t value Pr(>|t|) (Intercept) 1.192e-15 6.050e-16 1.969e+00 0.144 X 1.000e+00 1.824e-16 5.482e+15 <2e-16 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 Residual standard error: 5.769e-16 on 3 degrees of freedom Multiple R-squared: 1, Adjusted R-squared: 1 F-statistic: 3.005e+31 on 1 and 3 DF, p-value: < 2.2e-16 From this wee see that the estimated linear equation is y=x+1.192 and when we calculate the residuals for the first data point it should be 1-(1+1.92) -1.92. But why the residual output shows -4.8. How is the residual calculated here?