Number of Number of Elapsed days Elapsed days month days in month calendar month synodical month Error 1 30 30 29.53 -.47 2 29 59 59.06 .06 3 30 89 88.59 -.41 4 29 118 118.12 .12 5 30 148 147.65 -.35 6 29 177 177.18 .18 7 30 207 206.71 -.29 8 29 236 236.24 .24 9 30 266 265.78 -.22 10 29 295 295.31 .31 11 30 325 324.84 -.16 12 29 354 354.37 .37 13 30 384 383.90 -.10 14 29 413 413.43 .43 15 30 443 442.96 -.04 16 29 472 472.49 .49 17 30 502 502.02 .02 18 29 531 531.55 .55 19 30 561 561.08 .08 20 29 590 590.61 .61 21 30 620 620.14 .14 22 29 649 649.67 .67 23 30 679 679.20 .20 24 29 708 708.73 .73 25 30 738 738.26 .26 26 29 767 767.80 .80 27 30 797 797.33 .33 28 29 826 826.86 .86 29 30 856 856.39 .39 30 29 885 885.92 .92 31 30 915 915.45 .45 32 29 944 944.98 .98 33 30 974 974.51 .51 34 29 1003 1004.04 1.04