The Final 5 Days of My Parents’ Lives: June 15th

Have you ever wondered why anniversaries that are multiples of 5 or 10 are more significant milestones than those that are multiples of other numbers? I wonder if we had six fingers, instead of five, whether a 24th wedding anniversary might be a bigger deal than the 20th, and if we had seven fingers a 49th might be much more important than a 50th.