Interest on 1,000 at one percent, per week

Interest Per week
Percentage 1%
Amount 1,000

One percent of 1,000
1% of 1,000 is 10

Week
Interest for week is amount

10 x1 week is 10
10 x2 weeks is 20
10 x3 weeks is 30
10 x4 weeks is 40

One year 
10 x52 weeks is 520