To represent numbers up to 50 with base ten blocks, we can use a combination of units (ones), rods (tens), and flats (hundreds). Here’s how we can represent each number up to 50:

1: One unit 2: Two units 3: Three units 4: Four units 5: Five units 6: Six units 7: Seven units 8: Eight units 9: Nine units 10: One rod (10 units) 11: One rod and one unit 12: One rod and two units 13: One rod and three units 14: One rod and four units 15: One rod and five units 16: One rod and six units 17: One rod and seven units 18: One rod and eight units 19: One rod and nine units 20: Two rods (20 units) 21: Two rods and one unit 22: Two rods and two units 23: Two rods and three units 24: Two rods and four units 25: Two rods and five units 26: Two rods and six units 27: Two rods and seven units 28: Two rods and eight units 29: Two rods and nine units 30: Three rods (30 units) 31: Three rods and one unit 32: Three rods and two units 33: Three rods and three units 34: Three rods and four units 35: Three rods and five units 36: Three rods and six units 37: Three rods and seven units 38: Three rods and eight units 39: Three rods and nine units 40: Four rods (40 units) 41: Four rods and one unit 42: Four rods and two units 43: Four rods and three units 44: Four rods and four units 45: Four rods and five units 46: Four rods and six units 47: Four rods and seven units 48: Four rods and eight units 49: Four rods and nine units 50: Five rods (50 units)