20110324 add use of sequence (FG)
20110324 add exercise from module module=E1/number/oefcalcul1.fr
20110324 add exercise from module E4/number/oefcalcul.fr (FG)
20110324 add exercise from module E6/number/oefcascade.fr (FG)
20110321 add exercise in sheet3 and sheet9 (FG)

