The 2 images below are from SEAB website as of July'2018.
You may wish to visit the link below to check for any updated information given.
Link: https://www.seab.gov.sg/pages/nationalExaminations/PSLE/syllabuses
Standard Mathematics
Foundation Mathematics
Link: https://www.seab.gov.sg/docs/default-source/national-examinations/syllabus/psle/2018_psle_subject_info/0038_2018_16052018.pdf